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New Malicious Program by Creators of Stuxnet Is Suspected

The designers of Stuxnet, the computer worm that was used to vandalize an Iranian nuclear site, may have struck again, security researchers say.

Stuxnet, which infected tens of thousands of computers in 155 countries last year, created an international sensation when experts reported that it was designed as an American-Israeli project to sabotage Siemens Corporation computers used in uranium enrichment at the Natanz site.

The researchers say the new malicious program, which they call Duqu, is intended to steal digital information that may be needed to mount another Stuxnet-like attack.

The researchers, at Symantec, announced the discovery on the company’s Web site on Tuesday, saying they had determined that the new program was written by programmers who must have had access to Stuxnet’s source code, the original programming instructions.

“Duqu’s purpose is to gather intelligence data and assets from entities, such as industrial control system manufacturers, in order to more easily conduct a future attack against another third party,” the Symantec researchers said. “The attackers are looking for information such as design documents that could help them mount a future attack on an industrial control facility.”

They said the Duqu program was found in Europe in a narrowly limited group of organizations, “including those involved in the manufacturing of industrial control systems.”

In contrast to Stuxnet, Duqu has been found in only a handful of organizations to date. The program is designed to last 36 days and then remove itself from the system it infected.

Like Stuxnet, Duqu tries to prove its authenticity by using a stolen digital certificate, this one apparently taken from a Taiwanese company. Symantec officials were able to revoke the security certificate after it was discovered stolen because the company owns the VeriSign authentication service that controls the certificate infrastructure.

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The Symantec posting, and a related technical paper, raised a new mystery of its own. The company said it had been alerted to the new malware by a “research lab with strong international connections,” but declined to identify it further or say whether it was governmental or private.

According to Vikram Thakur of Symantec, the organization decided not to come forward because it wanted to protect the identity of the victim organization. The technical paper did include this comment from the team that apparently discovered the malware: “As we are in academia, we have limited resources to analyze malware behavior.”

Mr. Thakur added that in the two days since Symantec had received its initial malware sample, the security firm had received other variants of the program, which also appear to be aimed at makers of industrial control equipment.

The researchers identify a wide variety of similarities between Duqu and Stuxnet and said that the new program could not have been written without having access to the original programmer’s instructions. It has been previously noted that Stuxnet had both an attack capability as well as the ability to spy on the computers it infiltrated.

Security researchers have argued that the Stuxnet attackers were able to gather valuable intelligence information about the Iranian nuclear program as well as damage the control equipment at Natanz.

The Symantec researchers said they had not been able to determine how the Duqu code reached its target. Stuxnet used a wide range of system vulnerabilities, leading to speculation that it could have been written only by an organization with the resources of a national intelligence agency. Mr. Thakur said of Duqu, “This is extremely sophisticated, this is cutting edge.”

Correction: October 21, 2011

Because of an editing error, an article on Wednesday about a malicious new program thought to be created by the designers of the Stuxnet computer worm referred incorrectly to the method by which the new program, called Duqu, gains access to digital data. Duqu is a Trojan horse program, not a worm. The error was repeated in the headline.

A version of this article appears in print on October 19, 2011, on Page B6 of the New York edition with the headline: New Worm By Creators Of Stuxnet Is Suspected. Order Reprints|Today's Paper|Subscribe